Bypass and demand pump and valve system for bypass and demand pump

ABSTRACT

A diaphragm pump such as a three-chamber diaphragm pump includes a head having an inlet port and an outlet port and defining an inlet side including inlet chambers; and an outlet side having a center outlet chamber. Each of the inlet chambers includes an associated inlet valve. A single shutoff valve controlling fluid flow to the center outlet chamber and a single bypass valve in fluid communication between the center outlet chamber and the inlet side. The single shutoff valve has a plunger with an oval cross-section extending into the center outlet chamber. The single shutoff valve and the single bypass valve have adjustable pressure set points that are adjustable independently of one another.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention is directed to an improved pump and valve systemoperable in a bypass mode and a demand mode and to a method of operatingsuch a pump.

Description of the Prior Art

Positive displacement pumps and in particular diaphragm pumps, are usedfor various types of applications. Depending upon the type ofapplication, the requirements for the pump and controlling flow andpressure may vary widely. Such pumps are often broadly categorized aseither a demand pump or a bypass pump.

Demand type pumps are often used where a set flow and pressure arerequired. Common applications may include a spray wand for agriculturalspot spraying. For such a use, when the release valve such as found in awand is closed, pressure increases to a preset limit and the pressureswitch shuts off the motor. However, the pump has valves that trappressure in the line. Therefore, when the end release valve is open, thewand is turned back on and pressure in the line may decrease untilfalling below a set point that restarts the pump. Operating in such ademand mode is typically more stressful to the pump. However, this maynot be a satisfactory configuration where variable rates are required.

In contrast to demand pumps, bypass pumps are suited for use where awide range of flows and pressures may be required. An example of acommon use as is a spray bar having nozzles that are independentlycontrolled and may have independent flow needs. In a bypass pump, thepump remains on regardless of the pressure in the system. For suchsystems, flow rate may vary such as when one nozzle is in operation asopposed to two or more nozzles are being utilized. If there are nozzlesthat are not utilized, the excess flow is not delivered from the pump,but is bypassed within the pump. Such pumps must be configured toaccommodate the highest flow requirements for the system. Bypass pumpsprevent problems associated with repeated on and off cycling of thepumps, which may burn out the pump motor.

Although it may be possible to utilize both a bypass operatingconfiguration and a demand operating configuration, the added controland flow for each operating mode typically requires additional controland/or flow elements that may enlarge the pump and may make itimpractical for many applications. Although pumps have been developedthat may be able to function as a demand pump or a bypass pump, thecompact configuration of lower flow diaphragm pumps does not providesufficient space for valves and controls to operate satisfactorily inboth demand mode and a bypass mode without increasing the size of thehead.

Moreover, demand pumps and bypass pumps of similar capacities requiredifferent housings. The same capacity bypass pump and demand pump wouldtypically have a different style housing. The manufacture of suchhousings, which are typically molded, would be improved if a single moldwith removable mold inserts could be utilized in a method for creating abypass pump housing, a demand pump housing, or a combination bypass anddemand pump housing mountable to the same motor.

It can be seen then that a new and improved pump and valve system areneeded that can be operated as both a demand pump and as a bypass pump.Moreover, such a pump should be simple and inexpensive to manufacture.Such a pump should be sufficiently compact and have a compact valvesystem so that it does not occupy additional volume to make the valvesystem impractical. Moreover, such a pump system should be configured sothat the same housing may be utilized with different mold inserts toallow for making interchangeable housings for a demand pump, for abypass pump, or for a combination demand and bypass pump. The demand andbypass pressure settings should be adjustable independently of oneanother in the same pump. The present invention addresses these as wellas other problems associated with demand and bypass pumps.

SUMMARY OF THE INVENTION

The present invention is directed to a diaphragm pump with a valvesystem operable in bypass mode and in a demand mode. The pump includes ahead and a motor. The head includes a lower housing assembly and anupper housing assembly. A valve plate assembly is mounted intermediatethe upper housing assembly and the lower housing assembly. A shutoffswitch housing mounts to the upper housing assembly.

A drive shaft extends from the motor, drives the components in the head,and operates the diaphragm and valves. A cam mounts on the drive shaftand within a bearing and drives a wobbler. As the drive shaft rotatesthe wobbler or wobble plate with a face angled at approximately 3-4.5degrees “wobbles” to convert axial motion into linear motion of thewobbler. The linear motion of the wobbler stretches and deforms thediaphragm to create a pumping action. The pump may typically includethree or more chambers and includes an inlet valve for each chamber. Asthe wobbler rotates and oscillates back and forth by the cam, thediaphragm is deformed back and forth to pump fluid. The valves fit intothe valve plate assembly that spaces the three valves and chambers andis engaged by the diaphragm. The discharge valve mounts on the oppositeside of the valve plate assembly. The discharge valve forms a seal thatengages an inner portion of the upper housing assembly, as explainedhereinafter.

The upper housing assembly includes sliding connectors at the fluidports. Such connectors allow for snapping in complementary fluid linesto provide a quick disconnect. Alternatively, the ports may have aconventional threaded connector for connection to a complementarythreaded connector of a fluid line. The connectors are able toaccommodate adapters to mount fluid lines of different diameters to thepump.

The pumped fluid generally flows into an inlet port through the head andexits out an outlet port. The pumped fluid is initially drawn from theinlet port into the pumping chambers through the valve plate assembly bythe diaphragm. The pumped fluid then passes through an opening in thecenter of the valve plate assembly and through the outlet cavity to theoutlet port.

The pump of the present invention is configured for operation as eithera bypass pump or a demand pump. To accomplish this dual operation, aswitch adapter mounts to the upper housing and provides for mounting theshutoff valve switch assembly for the shutoff valve to the upperhousing. The switch adapter includes a gasket on one side and a neopreneseal on the opposite face. The upper housing also receives a bypassvalve housing in a triangular recess aligned with the bypass valve. Thebypass valve includes a flexible disc received in a complementaryshutoff valve chamber formed in the upper housing. The bypass valvechamber also spans the interior and exterior of the outlet cavity. Thetriangular recess on the exterior of the upper housing leads to thebypass valve chamber in the interior of the upper housing assembly. Abypass spring is engaged by guides that seat in the bypass valvehousing. An adjustment screw engages the bypass spring and provides forsetting a pressure at which fluid bypasses the outlet, as explainedhereinafter. Rotation of the adjustment screw in a first directioncompresses the bypass spring and rotation of the adjustment screw in anopposite direction allows the bypass spring to extend, thereby providingfor adjustment of the force of the spring acting on the disc and tocontrol the backpressure at which the disc deforms and allows fluid topass.

In addition, the pump functions as a demand pump with a shutoff switchincluding a housing base, a switch lever arm, a low pressure spring, anda micro-switch, all fitting into the switch housing, mounting onto theupper housing. The shutoff pressure may be adjusted independently byturning shutoff valve low pressure adjustment screw. Both the bypasspressure and the low pressure operating points for the pump can bemanually adjusted independently by accessing the bypass adjustment screwand the low-pressure adjustment screw from the exterior of the pump.However, the pressure points are typically set at the factory withcustomers prescribing a particular bypass pressure setting and a lowpressure shutoff setting. It can also be appreciated that the twopressure set points for bypass and shutoff are independently adjustableof one another without removal of the head or any components. With botha shutoff valve and a bypass valve, the pump is always in both a demandand a shutoff mode and has the superior characteristics and advantagesof each type of pump.

The three chambers each have an inlet valve and are opened and closed asthe wobbler rotates and stretches and deforms the molded diaphragm. Anoval shaped outlet cavity is formed by a cavity wall. The outlet cavityat least partially intersects with each of the three chambers. The checkvalve includes a plunger biased by a plunger spring. An oval O-ringprovides a seal against an oval cylinder receiving the plunger. It canbe appreciated that the oval shape of the plunger provides forsufficient volume and overlap with each of the three chambers. Thepresent invention therefore avoids having three separate bypass valvesfor each of the three chambers. The present invention saves furtherspace by having the plunger spring positioned within a void formed inthe stem extending from the plunger.

The outlet chamber is also shaped as an oval to mate to the oval outletcavity and includes both a full circular valve portion as well as asemi-circular valve portion to adapt to the oval configuration. Thelocation and shape of the outlet valve provides for fluid communicationwith each of the triangular spaced chambers. Moreover, the wobble plateprovides for deforming different portions of the diaphragm so that atall times, one of the chambers is substantially closed, one of thechambers is substantially pumping fluid out and one of the chambers isdrawing fluid into the chamber. Therefore, constant flow is maintainedwhile the pump is in operation.

In operation, the pump may be shut off with zero flow; in anotheroperating condition, the pump may be in a free flowing operatingcondition; and in a further operating condition, the pump may beoperating, but bypassing fluid. In the first operating condition, thereis no flow inside the pump head. The shutoff check valve is in the fullyclosed position and the bypass valve is in the fully closed position. Insuch a state, there is insufficient demand or backpressure to open theshutoff valve.

In a second operating condition, the pump is in an open flow conditionwith no restriction and no backpressure inside the pump head. Theshutoff check valve is in a fully opened position. Moreover, the bypassvalve remains fully closed. There is no backpressure within the head andall fluid to be pumped passes through the pump.

In a third operating condition, the pump is in a bypass mode. There isrestricted flow inside the pump head and there is built up backpressure.The shutoff check valve is in a fully open position. The bypass valve isin an open position due to restriction of flow and the associatedbackpressure. In such a condition, the flexible stamped disc is deformedto act as a valve member and allow the fluid to bypass back into thepump head. The fluid to be pumped flows through the bypass valve chamberand circulates within the head in the volume exterior of the outletcavity and on the inlet side of the upper housing. The pump remains inthis state until there is sufficient pressure so that the shutoff valveengages. The pump of the present invention therefore avoids the problemsrelated to repetitive cycling on and off and possibly burning out pumpmotors and wearing other pump elements.

It can be appreciated that the compact geometry of the pump head iscritical in achieving a demand and bypass pump that is operable in bothmodes and has each of the pressure points adjustable independently.Moreover, the present invention is able to achieve such a demand andbypass pump with a single shutoff switch and a single check valve. Theoval geometry of the plunger and the complimentary oval cylinder achievea sufficient valve area to function in a satisfactory manner withoutrequiring enlargement of the surrounding pump components. Moreover, thebypass valve chamber and the bypass valve are also configured forproviding operation to the multiple chambers with a single bypass valve.

The unique geometry also achieves production advantages for such a pump.The upper housing assembly provides for receiving both a shutoff switchassembly, a check valve and a bypass valve assembly. However, for manyapplications, such flexibility of both demand and bypass may not beneeded. With the present invention, the molded upper housing assemblymay simply include a separate insert to block the shutoff check valvefor use while retaining the bypass valve so that the pump is a bypassvalve and functions in that mode. However, with a second differentinsert, the head may be molded with the bypass valve blocked, while theshutoff valve remains so that the pump functions as a demand pump. In athird configuration of molding the upper housing assembly, the mold isconfigured so that both the oval cylinder and bypass valve chamber aremolded into the upper housing assembly. Therefore, the same basichousing assembly with different mold inserts may be molded for use as ademand pump, for use as a bypass pump, or for use as a combinationbypass and demand pump. The other shutoff valve components are simplyeliminated if the pump is configured as a bypass pump and the otherbypass valve components are eliminated if the pump is configured as ademand pump.

These features of novelty and various other advantages that characterizethe invention are pointed out with particularity in the claims annexedhereto and forming a part hereof. However, for a better understanding ofthe invention, its advantages, and the objects obtained by its use,reference should be made to the drawings that form a further parthereof, and to the accompanying descriptive matter, in which there isillustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, wherein like reference numerals andletters indicate corresponding structure throughout the several views:

FIG. 1 is a perspective view of a pump according to the principles ofthe present invention;

FIG. 2 is an exploded perspective view of the pump in FIG. 1;

FIG. 3 is a front elevational view of the upper housing assembly for thepump shown in FIG. 1;

FIG. 4 is a rear elevational view of the upper housing assembly shown inFIG. 3;

FIG. 5 is a side view of the upper housing assembly shown in FIG. 3;

FIG. 6 is an exploded view of the upper housing assembly shown in FIG.3;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 4 with the pumpin a first operating condition with the check valve and the bypass valveboth fully closed and no flow inside the head;

FIG. 8 is a sectional view taken along line 7-7 of FIG. 4 with the pumpin a second operating condition with the check valve fully open, thebypass valve fully closed and open flow in the head;

FIG. 9 is a sectional view taken along line 7-7 of FIG. 4 with the pumpin a third operating condition with the check valve fully open, thebypass valve open due to back pressure and restricted flow in the head;

FIG. 10 is a sectional view taken along line 10-10 of FIG. 4 and fluidflow through the upper housing assembly; and

FIG. 11 is an exploded side view of the head showing fluid flow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and in particular to FIG. 1, there isshown a diaphragm pump, generally designated (100). The pump (100)includes a head (102) and a motor (104). The pump (100) mounts with abracket (180) to other structure and is powered by a cord (182). Thehead (102) includes a lower housing assembly (106) and an upper housingassembly (110). A valve plate housing assembly (108) is mountedintermediate the upper housing assembly (110) and the lower housingassembly (106). A shutoff valve housing (150) mounts to the upperhousing assembly (110). The housings (106, 108, 110, 150) are connectedtogether and to the motor (104) with hardware (168).

Referring now to FIG. 2, extending from the motor (104) is a drive shaft(126) that drives the components in the head (102) and actuates a moldeddiaphragm (116) and valves (114) and (122). A cam (118) mounts on thedrive shaft (126) and within a bearing (120) and drives a wobbler (112).As the drive shaft (126) rotates the wobbler (112) or wobble plate moveswith an angled face at an angle of approximately 3-4.5 degrees toconvert axial motion into linear motion of the wobbler (112). The linearmotion of the wobbler (112) stretches and deforms portions of the moldeddiaphragm (116). In the embodiment shown, the pump (100) includes threechambers and includes three inlet valves (114). As the wobbler (112)rotates and oscillates back and forth or “wobbles” by the cam (118), thefluid is pumped through the upper housing assembly (110). The inletvalves (114) fit into the valve plate assembly (108) that spaces thethree valves and chambers and are engaged by the diaphragm (116). Thedischarge valve (122) mounts on the opposite side of the valve plateassembly (108). The discharge valve (122) forms a seal (124) thatengages an inner portion of the upper housing assembly (110), asexplained hereinafter.

The head (102) includes sliding connectors (172) at inlet fluid port(170A) and outlet port (170B). Such connectors (172) allow for a quickconnect/disconnect of complementary fluid lines. It can also beappreciated that the ports (170A, 170B) may have conventional threadedconnectors for connection to complementary threaded connectors of afluid line. The sliding connectors (172) are able to accommodate anadapter to mount fluid lines of different diameters to the pump (100).

Referring now to FIG. 11, there is shown the general fluid flow throughthe pump head (102). The pumped fluid generally flows through an inletport (170A) through the head (102) and exits through an outlet port(170B). The pumped fluid is initially drawn from the inlet port (170A)into the pumping chambers (200A), (200B) and (200C) through the valveplate assembly (108) by the diaphragm (116). The pumped fluid thenpasses through an opening in the center of the valve housing plate (108)and through the outlet cavity (202) to the outlet port (170B).

The pump (100) of the present invention is configured for operation as abypass pump and as a demand pump. As shown in FIGS. 3-6, to accomplishthis dual operation, a shutoff check valve (128) is actuated by ashutoff valve switch (140) that attaches to a switch adapter (138)mounted to the upper housing (110) and provides for mounting the shutoffvalve switch assembly (140) to the upper housing (110). The switchadapter (138) includes an O-ring (136) on one side and a seal (154) onthe opposite face.

A bypass valve (156) includes a bypass valve housing (164) insertinginto a triangular recess (210) in the exterior of the upper housing(110) aligned with a bypass valve chamber (208) on the interior of theupper housing (110). The bypass valve (156) includes a flexible disc(158) received in a complementary bypass valve chamber (208) formed inthe upper housing (110). The bypass valve chamber (208) intersects theinterior and exterior of the outlet cavity (202), as shown in FIG. 4.The triangular recess (210) on the exterior of the upper housing (110)leads to and fluidly connects to the bypass valve chamber (208) in theinterior of the upper housing assembly (110). A bypass spring (160) isengaged by guides (162) that seat into the bypass valve housing (164).Adjustment screw (166) engages the bypass spring (160) and provides forsetting a pressure at which fluid bypasses the outlet, as explainedhereinafter. Rotation of the adjustment screw (166) in a first directioncompresses the bypass spring (160) and rotation of the adjustment screw(166) in an opposite direction allows the bypass spring (160) to extend,thereby providing for adjustment of the force of the spring (160) actingon the disc (158) to control the backpressure at which the disc (158)deforms and allows fluid to pass.

In addition, the pump (100) functions as a demand pump with the checkvalve (128) controlled by the shutoff switch (140). The shutoff switchassembly (140) includes a housing base (144), a shutoff switch lever arm(142), a low pressure spring (146), and a micro-switch (160), allfitting into the shutoff switch housing (150), mounting onto the upperhousing (110). The shutoff pressure may be adjusted independently byturning shutoff valve low pressure adjustment screw (152). Rotation ofthe adjustment screw (152) in a first direction compresses the lowpressure spring (146) and rotation of the adjustment screw (152) in anopposite direction allows the low pressure spring (146) to extend,thereby providing for adjustment of the force of the spring (146) actingon the shutoff switch lever arm (142) and to control the pressure atwhich the micro-switch (160) activates to open or close the check valve(128) and allow fluid to pass. Therefore, both the bypass pressure andthe low pressure operating points for the pump (100) can be manuallyadjusted independently by accessing the bypass adjustment screw (166)and the low pressure adjustment screw (152) from the exterior of thepump (100). However, the pressure points are typically set at thefactory with customers prescribing a particular bypass pressure settingand a low pressure shutoff setting. It is also appreciated that the twopressure set points for bypass and shutoff are independently adjustableof one another without removal of the head or any components. As thepump (100) has both a shutoff valve (128) and a bypass valve (156), thepump (100) is always in both a demand mode and a shutoff mode and hasthe superior characteristics and advantages of each type of pump.

The three chambers (200A), (200B), (200C) each have an inlet valve (114)and are opened and closed as the wobbler (112) rotates to deformportions of the molded diaphragm (116). An oval outlet cavity (202) isformed by a cavity wall (204). The outlet cavity at least partiallyintersects with each of the three chambers (200A), (200B), (200C). Thebypass valve (156) includes a plunger (130) biased by a plunger spring(132). An oval gasket (134) provides a seal against an oval cylinder(206) receiving the plunger (132). It can be appreciated that the ovalshape of the plunger (130) provides for sufficient volume in a smallspace with the outlet cavity (202) that overlaps with each of the threechambers (200A), (200B) and (200C). The present invention thereforeavoids having three separate bypass valves, one for each of the threechambers, as needed with other systems. The present invention savesfurther space by having the plunger spring (132) within a cylindricalspace formed in the rod extending from the back of the plunger (130).

The outlet valve (122) is a molded element shaped as an oval to mate tothe oval outlet cavity (202) and includes both a full circular valveportion as well as a semi-circular valve portion to adapt to the ovalconfiguration. The location and shape of the outlet valve (122) andoutlet cavity (202) provides for fluid communication with each of thetriangular spaced chambers (200A), (200B) and (200C). Moreover, thewobble plate (112) provides for stretching the diaphragm (116) so thatat all times, one of the chambers (200A), (200B) or (200C) issubstantially closed; one of the chambers is substantially pumping fluidout; and one of the chambers is drawing fluid into the chamber.Therefore, constant flow is maintained while the pump (100) is inoperation.

In operation, the pump (100) the pump (100) may be shut off with zeroflow; in another operating condition, the pump (100) may be in a freelyflowing operating condition; and in a further operating condition, thepump (100) may be bypassing fluid. Referring now to FIGS. 7-9, the pumpconfiguration of each of the modes and operating conditions is shown. InFIG. 7, there is no flow inside the pump head (102). The shutoff checkvalve (128) is in the fully closed position and the bypass valve (156)is in the fully closed position. In such a state, there is insufficientdemand or backpressure to open the shutoff valve (128).

Referring now to FIG. 8, the pump (100) is in an open flow operatingcondition with no restriction and no backpressure inside the pump head(102). The shutoff check valve (128) is in a fully opened position.Moreover, the bypass valve (156) remains fully closed. There is nobackpressure within the head (102) and all fluid to be pumped flowsthrough the pump (100).

Referring to FIG. 9, the pump is in a bypass operating condition. Thereis restricted flow inside the pump head (102) and there is built upbackpressure. The shutoff check valve (128) is in an open position. Thebypass valve (156) is in an open position due to restriction of flow andthe associated backpressure. In such a condition, the flexible stampeddisc (158) bows outward. When the disc (158) is deformed in this manner,the disc (158) acts as a valve member and allows the fluid to flowaround the periphery of the disc (158) and bypass back into the pumphead (102). The fluid to be pumped flows through the bypass valvechamber (208) and circulates within the head (102) in the volumeexterior of the outlet cavity (202) and on the inlet side of the upperhousing (110). The pump (100) remains in this state until there issufficient pressure that the shutoff valve (128) engages. The pump (100)of the present invention therefore avoids the problems related torepetitive cycling on and off and burning out pump motors and wearingother pump elements.

It can be appreciated that the geometry of the pump head (102) iscritical in achieving a demand and bypass pump that is operable in bothdemand and bypass modes and has each of the pressure points adjustableindependently. Moreover, the present invention is able to achieve such ademand and bypass pump with a single check valve (128) and a singlebypass valve (156). The oval geometry of the plunger (130) and thecomplimentary oval cylinder (206) achieve a sufficient valve area tofunction in a satisfactory manner without requiring enlargement orrearrangement of the surrounding pump components. Moreover, the bypassvalve chamber (208) and the bypass valve (156) are also configured forproviding operation to all of the multiple chambers with a same singlebypass valve. The oval profile of the plunger (130) and cylinder (206)also achieve adequate engagement and sealing.

The unique geometry also provides for advantages for producing such apump. It can be appreciated that in the embodiment shown, the upperhousing assembly (110) provides for receiving both a shutoff valveassembly (128) and a bypass valve assembly (156). However, for certainapplications, such flexibility of both demand and bypass may not beneeded. With the present invention, the molded upper housing assembly(110) may simply include a separate insert to block the shutoff checkvalve for use while retaining the bypass valve so that the pump is abypass valve and functions in that mode. However, with a second insert,the head (102) may be molded with the bypass valve blocked, while theshutoff valve (128) remains so that the pump functions as a demand pump.In a third configuration of molding the upper housing assembly (110),the mold is configured so that both the oval cylinder (206) and bypassvalve chamber (208) are molded into the upper housing assembly (110).Therefore, the same basic housing assembly with different mold insertsmay be molded for use as a demand pump, for use as a bypass pump, or foruse as a combination bypass and demand pump. The inlet and outlet valvesand chambers do not need to be modified. Moreover, the shutoff valvecomponents are simply eliminated if the pump is configured as a bypasspump and the bypass valve components are simply eliminated if the pumpis configured as a demand pump.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present invention have been setforth in the foregoing description, together with details of thestructure and function of the invention, the disclosure is illustrativeonly, and changes may be made in detail, especially in matters of shape,size and arrangement of parts within the principles of the invention tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

What is claimed is:
 1. A diaphragm pump comprising: a head comprising aninlet port and an outlet port and defining an inlet side including aplurality of inlet chambers; and an outlet side having a center outletchamber intermediate the plurality of chambers; a plurality of inletvalves, wherein each of the inlet chambers includes an associated inletvalve; a single shutoff valve controlling fluid flow to the centeroutlet chamber; a single bypass valve in fluid communication between thecenter outlet chamber and the inlet side.
 2. A diaphragm pump accordingto claim 1, the single shutoff valve comprising a plunger extending intothe center outlet chamber.
 3. A diaphragm pump according to claim 2,wherein the plunger comprises an oval cross section.
 4. A diaphragm pumpaccording to claim 1, wherein the plunger comprises a stem, the stemincluding a recess receiving a spring.
 5. A diaphragm pump according toclaim 1, wherein the plunger comprises a head with an oval cross sectionand a stem connected to the head, the stem including a recess receivinga spring.
 6. A diaphragm pump according to claim 1, wherein the singleshutoff valve and the single bypass valve have adjustable pressure setpoints.
 7. A diaphragm pump according to claim 6, wherein the pressureset points are independently adjustable.
 9. A diaphragm pump accordingto claim 1, wherein the pump comprises three inlet chambers.
 10. Adiaphragm pump according to claim 1, wherein head comprises three inletchambers arranged in a triangular configuration with the central outletchamber intermediate the three inlet chambers.
 11. A diaphragm pumpaccording to claim 1, further comprising a wobbler device actuating theinlet valves.
 12. A diaphragm pump according to claim 1, comprising asingle shutoff switch.
 13. A diaphragm pump system comprising: a headhaving a modular upper housing assembly, the modular housing assemblycomprising: a first interchangeable upper housing assembly configuredfor operation of the pump system solely as a demand pump; a secondinterchangeable upper housing assembly configured for operation of thepump system solely as a bypass pump; a third interchangeable upperhousing assembly configured for operation of the pump system as a demandpump or as a bypass pump.
 14. A diaphragm pump system according to claim13, wherein each of the interchangeable upper housing assembliesincludes three chambers in a triangular configuration and a centraloutlet chamber intermediate the three chambers.
 15. A method for makingan upper housing of a diaphragm pump, the method comprising: moldingusing a first mold for creating a first interchangeable housing; ormolding with the first mold and a first insert for creating a secondinterchangeable housing; or molding with the first mold and a secondinsert different from the first insert for creating a secondinterchangeable housing.
 16. A method according to claim 15, comprisingadding a switch to the diaphragm pump housing created with only thefirst mold.
 17. A method according to claim 15, comprising adding anattachment to the diaphragm pump housing created with the first mold andthe first insert.
 18. A method of operating a diaphragm pump as a demandpump and as a bypass pump, the diaphragm pump comprising: a headcomprising an inlet port and an outlet port and defining an inlet sideincluding a plurality of inlet chambers; and an outlet side having acenter outlet chamber intermediate the plurality of chambers; aplurality of inlet valves, wherein each of the inlet chambers includesan associated inlet valve; a single shutoff valve controlling fluid flowto the center outlet chamber; a single bypass valve in fluidcommunication between the center outlet chamber and the inlet side; themethod comprising: setting the single shutoff valve to a predeterminedshutoff pressure; and setting the single bypass valve to a predeterminedbypass pressure.
 19. A method of operating a diaphragm pump as a demandpump and as a bypass pump according to claim 18, wherein the bypasspressure is greater than the shutoff pressure.
 20. A method of operatinga diaphragm pump as a demand pump and as a bypass pump according toclaim 18, wherein the bypass pressure and shutoff pressure areindependently adjustable.
 21. A method of operating a diaphragm pump asa demand pump and as a bypass pump according to claim 18, wherein thebypass pressure and shutoff pressure are independently adjustable froman exterior of the pump.
 22. A head for a diaphragm pump; the headcomprising: an inlet port and an outlet port and defining an inlet sideincluding a plurality of inlet chambers; and an outlet side having acenter outlet chamber intermediate the plurality of chambers; aplurality of inlet valves, wherein each of the inlet chambers includesan associated inlet valve; a single shutoff valve controlling fluid flowto the center outlet chamber; a single bypass valve in fluidcommunication between the center outlet chamber and the inlet side.